Drill grinding machine



Dec. 16, 1969 'A. TATAR ,4

DRILL GRINDING MACHINE Filed NOV. 24, 1967 INVENTOR Alexander 7217A}?ATTORNEY nited States Patent O US. Cl. 51122 Claims ABSTRACT OF THEDISCLOSURE A drill grinding machine having a frame bearing a grindingwheel and a slidable drill holder, including a support stem for the workend of the drill to steady it during grinding, the support stem having amount arranged to adjust its position of engagement with the drill andbeing insulated from its mount to form part of an electrical signallingcircuit to show when it contacts the drill, the axis of the support stembeing at 90 to the axis of the drill and the drill holder being fixed tothe mount so as to follow its movements, the end of the support sternhaving a cutoff edge to clear the grinding wheel and an opposite grooveto support the drill end, and a stop plate in the plane of the grindingwheel optionally forming part of another electrical circuit to signalthe exact initial position of the drill for grinding.

BACKGROUND OF THE INVENTION Field of the invention Drill grindingmachines.

Description of the prior art In drill grinding machines known until now,the drill is supported in the neighbourhood of its extremity, either bythe aid of a simple support part or by means of a clamp. It isnecessary, to avoid any vibration or deformation of the drill, that thesupport part or the clamp acts on the drill as close as possible to itsend, on which the forces due to grinding are exerted.

In the case of clamps, relatively complicated and expensive solutionshave been proposed.

In the case of support parts, these cannot generally be positioned inthe immediate neighbourhood of the extremity of the drill, due to thefact that they then would prevent the passage of the grinding wheel.Moreover, the drill is generally applied laterally against the supportpart, so that is risks being broken if it is too roughly brought intocontact with the latter.

SUMMARY OF THE INVENTION It is an object of the present invention toovercome these drawbacks.

According to the invention there is provided a drill grinding machineincluding a frame, a grinding wheel and a drill holder to hold the drillrigidly during grinding operations, arranged on said frame so that thedrill can be moved opposite the grinding wheel and brought into variouspositions to enable the grinding of its different faces, said machinecomprising a support part for the drill to hold the drill by its end andprevent its deformation or subjection to vibration during grinding, amount on which said support part is mounted in a movable manner so as toenable it to be brought into engagement with the drill when the latteroccupies its initial grinding position, and an electrical warning deviceof which the supply circuit passes through the drill and through saidsupport part in such manner that the warning device functions when thesupport part comes into contact with the drill, thus signalling to theoperator that this contact is realized,

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in order to avoid the possibility of the operator straining or evenbreaking the drill by untimely continuation of the approach operation ofthe support part.

BRIEF DESCRIPTION OF THE DRAWING In order that the invention may be moreclearly understood one embodiment thereof is described below purely byway of illustrative but non-limiting example with reference to theaccompanying drawing in which:

FIGURE 1 is a view in front elevation of one embodiment of a drillgrinding machine according to the invention;

FIGURE 2 is a cross-sectional View along the line IIII of FIGURE 1, andon a larger scale;

FIGURE 3 is a view in elevation of a detail and on a still larger scale;

FIGURE 4 is a cross-sectional view along the line IV- IV of FIGURE 3, inwhich there is also shown a drill; and

FIGURE 5 is a cross-sectional view similar to FIG- URE 4, in which adrill of much smaller diameter is shown.

DESCRIPTION OF THE PREFERRED EMBODIMENT The machine comprises a frame 1,on which is mounted the motor 2 of a grinding wheel 3. Frame 1 has, onits front face, a transverse slide 4 on which a carriage 5 travels, thecarriage having a support 7 fixed thereto by a bolt 6, support 7 endingin a sleeve 7a on which a second support 8 is rotatably mounted, thesecond support, also ending in a sleeve, designated by 8a, in which ismounted a clamp or chuck 9 bearing the drill to be ground, which isdesignated by 10, which is thus held rigidly during grinding.

The direction of the slide 4 is parallel to the working plane ofgrinding wheel 3, which working plane is designated by 11 (FIGURE 2),and with which the outer face of a stop-plate 12 borne by a part 1a ofthe frame 1 is coincident, and against which the drill abuts axiallywhen it is placed in position on the machine, before grinding.

When the carriage 5 is displaced along the slide 4, the end of the drill1t), travelling in the plane 11, effects a translation in the course ofwhich it moves opposite the plate 12 and the grinding wheel 3.

The clamp 9 is mounted on the annular portion 8a of support 8 so as tobe axially displaceable, by means of a micrometric drum 13, rigidlyfixed to a threader sleeve 14, screwing into the inner tapping of abarrel 15. The latter is itself rotatably mounted on the annular part 8awhich is prevented from turning by a spring rod 16, subject to theaction of an opposing spring 17 engaged in one or other of a series ofholes 18 on the annular face of a shoulder or flange 15a of sleeve 15.This arrangement thus permits on the one hand, adpustment of the axialposition of the drill with respect to the support 8, and, on the otherhand, turning of the drill around itself to an angle corresponding tothe number of cutting lips of the drill, that is to say, generally, atan angle of which corresponds to the case where the drill has twocutting lips.

The rotation of support 8 around the axis of sleeve 7a of support 7,enables the tilting of the drill with respect to the plane of thegrinding Wheel, with a view to the grinding of two faces, cutting andclearance, of each cutting lip.

Sleeve 7a. is traversed by a barrel 19 in which is mounted, by means oftwo bushes 20 and 21, of insulating material, a stem 22 serving as asupport for the point of the drill. This stem is rigidly fixed axiallyto a micrornetric drum of which one part 23, of insulating material, isfixed to a tapped ring 24, screwing on the threaded end 19a of barrel19, which permits adjustment of the axial 3 position of stem 22 as afunction of the diameter of the drill to be ground. Stem 22 is precludedfrom turning on itself by a pin 25 engaged in a transverse slot 26 of aninsulating head 27, fixed by screws 28 to sleeve 19.

The axis of stem 22, designated by 29 (FIGS. 3 and 4), cuts the axis,designated by 30, of the drill, at the point of the latter, and forms anangle of 90 with it.

The end of support stem 22 has a cut-off face 31, (FIGS. 3 and 4), and aconical portion 32 in which is formed a V-shaped groove 33, of which thecorner constituting the bottom is situated in the plane of the axes 29and 30. The end of drill 10 is supported by the two walls boundinggroove 33. It should be noted that support stem 22 is positioned outsidethe axis of the drill and, thus, in no way interferes with the workingof grinding wheel 3, of which the active plane 11 has beendiagrammatically shown as 34 in FIGURE 4, while supporting the drill inthe immediate vicinity of its point, which prevents it from vibrating orbeing deformed during the operations of grinding; FIGURES 4 and showthat the smaller the diameter of the drill, the more support stem 22must approach the axis of the drill.

The adjustment of the machine is efiected by placing the drill to beground in clamp 9, then causing the latter to advance by means ofmicrometric drum 13 until the point of the drill abuts against stopplate 12.

The drill thus occupying axially an exact position called the initialposition, support stem 22 is advanced, by operation of micrometric drum23-24, until the wall of its V-shaped groove 33 comes into contact withthe drill. This contact is easily controllable due to the fact that themachine comprises a pilot light 35, (FIG. 1), of which the supplycircuit is closed when support stem 22, which is electrically insulatedfrom the body of the machine, comes into contact with the drill. Therear end 22a, of support stem 22, is reduced in a manner to constitute aplug on which is engaged a socket of an electrical conductor formingpart of the supply circuit of pilot light 35.

By means of this arrangement, the operator is immediately warned of theengagement of the support stem and the drill, thus avoiding untimelycontinuation of the advance of the stern, which would strain or evenrisk breaking the drill.

Pilot light 35 also ensures that the grinding is perfectly symmetrical.In fact, if, after having effected the grinding of two cutting lips of adrill, the latter is made to turn on itself, causing barrel 15 to turn,the pilot light must remain constantly lit, the contrary proving thatthe drill has an assymetry which it is advisable to correct by causingthe drill to advance slightly and repeating the grinding operation untilthe pilot light 35 remains lit for each of the two angular positions ofthe drill, indicating that the grinding is perfectly symmetrical.

It is to be noted that barrel 19 is rigidly fixed angularly to thesupport 8, so that support stem 22 turns at the same time as support 8when the latter is moved around the axis of sleeve 74: of support 7. Asa result, the drill remains supported in groove 33 of stem 22, whateverthe position of grinding.

Finally, it is to be noted that a modification of the angle of the pointof the drill may be obtained by causing support 7 to turn around itsfixing bolt 6, of which the vertical axis cuts that of the drill and issituated in the plane of the grinding wheel and of stop plate 12.

As a variation, stop plate 12 could be arranged in a manner to close theelectrical circuit of a pilot light 36, when the drill to be ground isin contact with it, indicating thus, during the positioning of the drillon the machine, that the drill has reached axially its exact initialposition of grinding.

It will be understood that various changes and modifications may be madein the embodiment described without departing from the essential conceptof the invention as defined in scope by the appended claims.

I claim:

1. A drill grinding machine including a frame, a grinding wheel and adrill holder to hold the drill rigidly during grinding operations,arranged on said frame so that the drill can be moved opposite thegrinding wheel and be brought into various positions to enable thegrinding of its different faces, said machine further comprising asupport part for the drill to hold the drill by its cutting end andprevent deformation or vibration during grinding, a mount on which saidsupport part is mounted in a movable manner so as to enable it to bebrought into engagement with the drill when the later occupies itsinitial grinding position, and an electrical warning device having asupply circuit passing through the drill and through said support partin such manner that the warning device functions when the support partcomes into contact with the drill, thus signalling to the operator thatthis contact is realized, in order to avoid straining or breaking thedrill by untimely continuation of the approach operation or' the supportpart.

2. A machine according to claim 1, wherein said sup port part comprisesa stem arranged so that its axis cuts that of the drill, said stem beingmounted on its mount in an axially movable manner and having an endwhich co-operates with the end of the drill.

3. A machine according to claim 1, wherein the axis of said support partforms an angle of with the axis of the drill.

4. A machine according to claim 1, wherein said support part comprises astem, of which the support end has an inclined surface with respect tothe axis of the stem, said support end having a V-shaped groove whosebottom is situated in the plane passing through the axes of the stem andthe drill, and by which groove the point of the drill can be supported.

5. A machine according to claim 1, wherein said support part is fixed tothe holder in a manner whereby said support part follows the movementsof the drill.

6. A machine according to claim 1, comprising an axial stop for thedrill, against which the drill can be supported when it occupies itsinitial position, prior to grinding, and an electrical signalling devicewhich comes into operation at the instant when the drill comes intocontact with said axial stop, to signal the operator that the initialaxial position of the drill has been achieved.

7. A machine according to claim 6, comprising a contact device situatedin the working plane of said axial stop to actuate the drill and closethe supply circuit of said electrical signalling device.

8. A machine according to claim 1, wherein said eletrical warning devicecomprises a pilot light which is lit when the drill and its support partare in contact with one another.

9. A machine according to claim 1, wherein the drill holder enables thedrill to be rotated about its longitudinal axis for grinding itsdifferent lips, the electrical warning device enabling control of thesymmetry of grinding by said rotation of the drill, in the course ofwhich, if the grinding has a fault of symmetry, the contact between thesupport part and the drill is interrupted, which is shown bycorresponding interruptions in the illumination of the pilot light.

10. A machine according to claim 5, wherein said mount and said drillholder are fixed to the frame by means of a part having a vertical axiswhich cuts the axis of the drill and is situated in the plane of thegrinding wheel.

References Cited UNITED STATES PATENTS

